Interdecadal variability along 38 degrees N in the North Atlantic.

摘要

Hydrographic data, in the time range from 1908 to 2006, extracted from the International Council for the Exploration of the Sea (ICES) database, are used to examine variability of water masses in the North Atlantic ocean along 38° N. All the data are interpolated in an ideal isopycnal framework, which has a longitudinal resolution of 1/3 degree and 50 isopycnal layers of variable thickness, to 38° N by using an objective analysis approach. Due to the limited number of data, a 5 year-running mean triad analysis is performed from 1950 to 2004 for further variability study. Extensive decadal to inter-decadal variability is observed, in both shallow and deep layers. Important water masses showing significant variability include those of the Deep Western Boundary Current (DWBC). In the deep layers, a signal of westward phase propagating is detected, coincided with the time scale of a first mode baroclinic Rossby wave transporting at this latitude. Strong negative correlations (maximum at a lag of 7 years) are seen between the variability in the DWBC and the North Atlantic Oscillation. A similar correlation at the same lag is also detected in the basin interior, suggesting the Labrador Sea Water (LSW) pathway is not only restrained to the DWBC.